APPENDIX B
FILM-BADGE CALIBRATION AND DEVELOPMENT
B.1
B.1.1
GENERAL
Radiation Standards
The primary radiation standard for calibration of film badges used at the Pacific Proving
Grounds was radium. This standard offers the closest approximation to the energy spectrum
of fission products available. Where Co” sources wereutilized, correction was applied, where
necessary, to producé results consistent with radium. The stronger Co™ source available was
utilized mainly because of the shorter exposure time required.
B.1.2
Range of Calibration
The low-range film was calibrated from 40 mr to 10 r and the high-range film from 10 to
60 r. This curve was extended to 200 r on the initial calibration. Additional extensions were
obtained only if needed.
Frequency
A new calibration curve was obtained whenever developing solutions were changed and between all shots. In addition, changes in developing procedure, poor temperature control,
changes in emulsion, or excessive correction factors required recalibration.
B.2
B.2.1
ieengl
B.1.3
CALIBRATION PROCEDURE
Range Construction
A variable distance-constant time calibration range was constructed,utilizing a 4- by 8-ft
plywood sheet. Exposure and distance relationships are as follows for the 2.64-curie Co®
source:
6-min exposure
Distance,
cm
Dose,
mr
Distance,
cm
Dose,
mr
24
29.4
60,000
40,000
65.3
75.5
800
600
33.7
41.4
30,000
20,000
92.9
106
64
400
300
Rae OF
1-hr exposure